The increase of beta-lactamase producing bacteria in the infections of the superior airways is a reality. Five to 30% of H. influenza and 40 to 70% of the M. catarrhalis are resistant to beta-lactamic antibiotics. The cefpodoxima proxetil is an oral cephalosporin antibiotic with wide bactericidal spectrum, resistant to most of the betalactamases. The efficacy and safety of cefpodoxima proxetil (400mg/day for 5 days) compared to the cefaclor (1.500mg/day for 10 days) in the treatment of the acute sinusitis was analyzed in 118 adult patients attended in the Otolaryngology Department of the Hospital das Clínicas and Santa Casa of São Paulo. Clinical, radiological and laboratorial evaluation were performed before and after treatment. The demographic aspects of the groups were similar. There was no statistical differences regarding the efficacy nor safety of both drugs. Blood tests after treatment were altered only in some patients who used cefaclor. We concluded that cefpodoxima proxetil and cefaclor were similar in efficacy and safety for the treatment of acute sinusitis in adult patients.